刷新ArrayList以使用单击微调器向RecyclerView显示新数据项目
问题描述:
单击Spinner
将新数据添加到RecyclerView
而不删除旧数据的项目。刷新ArrayList以使用单击微调器向RecyclerView显示新数据项目
一样,我有一个微调two
项目:Appliances
和Accessories
。
默认情况下,我显示Appliances
数据为RecyclerView,但每当我做tap
上配件 - 这正显示出Accessories data
到RecyclerView,但below Appliances data
,而我期待只有Accessories
数据到RecyclerView
MainActivity.java:
public class MainActivity extends AppCompatActivity {
.....
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_menu_screen);
.........
stringList = new ArrayList<String>();
stringList.add("Appliances");
stringList.add("Accessories");
ArrayAdapter<String> stringArrayAdapter = new ArrayAdapter<String>(MainActivity.this,
android.R.layout.simple_dropdown_item_1line,
stringList);
spinnerMenu.setAdapter(stringArrayAdapter);
......
initializeAdapter();
.....
spinnerMenu.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
@Override
public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
switch (position) {
case 0:
presenter.loadAppliances();
break;
case 1:
presenter.loadAccessories();
break;
}
}
@Override
public void onNothingSelected(AdapterView<?> parent) {
}
});
.......
}
public void initializeAdapter() {
categoryAdapter = new CategoryAdapter(this, new ArrayList<Category>());
mRecyclerView.setAdapter(categoryAdapter);
}
public void addMenu(List<Category> posts) {
categoryAdapter.addAllData(posts);
categoryAdapter.notifyDataSetChanged();
}
}
CategoryAdapter.java:
@Override
public int getItemCount() {
return posts.size();
}
public void setPosts(List<Categories> posts) {
this.posts = posts;
}
public void clearData() {
posts.clear();
}
public void addAllData(List<Categories> posts) {
this.posts.addAll(posts);
}
}
答
首先清除旧的ArrayList并将数据添加到Arraylist中。
public void addMenu(List<Category> posts) {
categoryAdapter.addAllData(posts);
categoryAdapter.notifyDataSetChanged();
}
public void addAllData(List<Categories> posts) {
this.posts.clear();
this.posts.addAll(posts);
}
答
您需要的时候选择了一个项目复位适配器。所以试试这个:
public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
initializeAdapter();
//after this the switch case
我也建议你有办法知道微调菜单的位置。 第一menupresenter.loadAppliances();
后有int positionSelected = 0;
然后在开关的情况下,
switch position
case: 0
if(positionSelected != 0) {
initializeAdapter();
menupresenter.loadAppliances();
positionSelected = 0;
}...
case: 1
if(positionSelected != 1) {
initializeAdapter();
menupresenter.loadAccessories();
positionSelected = 1;
}...
这将确保你不会复位recyclerView适配器不必要的。就像正在显示appliaces数据和用户一样,在下拉菜单中再次选择设备
为什么它被低估?我不认为这是我发布的错误。 – Sophie
嘿在调用'menuPresenter.loadAppliances();'之后清空你的列表'并且在调用'notifyDataSetChanged()' –
尝试过但得到空指针异常 – Sophie